Implementing the new kelvin 2

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WP4 (PTB, Aalto, RHUL, VTT)

Primary low-temperature thermometry

perform research in the ultra-low thermometry regime (0.9 mK to 1 K) so as to demonstrate the use of primary thermometers to disseminate of thermodynamic temperature,

demonstrate the consistency of the developed techniques and provide new data to ascertain the relation between thermodynamic temperature and the PLTS-2000 and resolve the discrepancy in the PLTS-2000 background data,

provide guidelines for realising thermodynamic temperatures with the developed techniques and

facilitate the take up of the ultra-low temperature developments by the measurement supply chain.

Extend working range of primary low-temperature thermometers

The aim of this task is to extend the working range of primary thermometers (CSNT - Current sensing noise thermometer, CBT - Coulomb blockade thermometer and pMFFT - primary magnetic field fluctuation thermometer) to the ultra-low temperature region around 0.9 mK with a target uncertainty of 1%. Currently the mentioned thermometers have been shown to agree within uncertainties of about 1.5% in the temperature range from 200 mK to 15 mK.

Magnetic field fluctuation thermometer

Resolve the PLTS-2000 background data discrepancy

The aim of this task is to investigate the consistency of the new realisation techniques to resolve the discrepancy in the background data of the PLTS-2000 by determining new T-T2000 data. The focus here is especially on temperatures in the range from around 20 mK down to 0.9 mK. To resolve the discrepancy new determinations of thermodynamic temperature are required, which have to be compared with high accuracy realisations of the PLTS-2000 provided by different laboratories. The uncertainty target for the determination of thermodynamic temperatures to reliably identify the cause of the background data discrepancy is 1%.

Guidance for use of the primary thermometers

The aim of this task is to develop guidance for the use of the primary thermometers developed in this project to be included in the MeP–K-19. The current version of the MeP-K contains only information for the realisation of the international temperature scales. With the redefinition of the unit kelvin in 2018 the MeP-K will be updated to include methods for primary thermometry. The work of this task will provide the necessary information to enable users to perform measurements of temperature in accord with the International System of Units using low-temperature primary thermometers.

Practical primary thermometers for the dissemination of T

The aim of this task is to develop practical primary thermometers for the dissemination of T and to improve practical temperature realisations in the range from ultra-low temperatures to around 1 K to underpin the uptake of primary thermometry by the measurement supply chain. This will be a direct dissemination of the new kelvin without any recourse to a defined scale.